Rotary drag valve

ABSTRACT

A valve assembly comprising a rotary closure element which defines an axis of rotation and is selectively movable between a fully open position and a fully closed position. Mounted to and movable with the rotary closure element is an impedance assembly. The impedance assembly defines an inflow end and an outflow end, and comprises a plurality of fluid passageways which extend from the inflow end to the outflow end. Also partially defined by the impedance assembly is a flow opening which extends from the inflow end to the outflow end. The fluid passageways and the flow opening are oriented relative to each other such that a portion of a flow through the valve assembly is directed into the fluid passageways and a portion of the flow is directed through the flow opening when the closure element is in the fully open position.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of U.S.application Ser. No. 10/122,276 entitled DRAG BALL VALVE filed Apr. 12,2002.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

[0002] (Not Applicable)

BACKGROUND OF THE INVENTION

[0003] 1. Field of the Invention

[0004] The present invention relates generally to rotary valves, andmore particularly to an energy attenuating ball valve which includes animpedance assembly mounted within and movable with the closure elementor “ball” of the ball valve.

[0005] 2. Discussion of Background

[0006] There is currently known in the prior art linear valve assemblieswhich are outfitted to include a noise attenuation or impedanceassembly. Such valves are often referred to in the relevant industry as“drag valves”. Linear valves as currently known in the prior arttypically include an annular impedance assembly which includes aplurality of annular disks which each define a plurality of radiallyextending, tortuous flow passages and are secured to each other in astacked arrangement. Disposed within the interior of the impedanceassembly is a piston which is cooperatively engaged to an actuatoroperative to facilitate the reciprocal movement of the piston within theimpedance assembly. When the piston is in a lowermost position, none ofthe passages of the impedance assembly are exposed to an incoming flow.As the piston is moved upwardly toward an open position, flow passesthrough the passages of the impedance assembly to provide an exit flowthrough the linear valve. The amount of flow through the impedanceassembly is varied by the position of the piston, which in turn variesthe area or proportion of the impedance assembly exposed to the incomingflow within the interior thereof.

[0007] Though the above-described linear valve arrangement providessignificant noise reduction capabilities, in certain applications it isoften desirable to employ the use of a rotary valve utilizing a rotaryclosure element as an alternative to a linear valve. Since currentlyknown linear impedance valves are typically considered to providesuperior noise reduction capabilities as compared to rotary valves, thepresent invention addresses this disparity by providing a rotary valvearrangement which retains the benefits o the impedance assemblyassociated with linear valves, while still employing the use of a rotaryclosure element. As will be discussed in more detail below, in thepresent invention, the impedance assembly is carried by the rotaryclosure element of the rotary or ball valve which may be adapted for usein large, high capacity applications for which an equivalent linearvalve would be excessively expensive (attributable to manufacturingobstacles) and potentially susceptible to instability problems. These,and other advantages of the present invention, will be discussed in moredetail below.

BRIEF SUMMARY OF THE INVENTION

[0008] In accordance with the present invention, there is provided avalve assembly comprising a rotary closure element defining an axis ofrotation and selectively movable between a fully open position and afully closed position. Mounted to and movable within the rotary closureelement is an impedance assembly. The impedance assembly defines aninflow end and an outflow end, and comprises a plurality of fluidpassageways which extend from the inflow end to the outflow end. Theimpedance assembly also partially defines a flow opening which extendsthrough at least a portion of the bore of the rotary closure elementinto which the impedance assembly is mounted. The fluid passageways andsuch flow opening are oriented relative to each other such that aportion of flow through the valve assembly is directed into the fluidpassageways, with a portion of the flow being directed through the flowopening when the closure element is in its fully open position.

[0009] The fluid passageways may be disposed, in their entirety,downstream of the axis of rotation of the closure element when the sameis in its fully open position. Alternatively, the impendence assemblymay be formed such that certain ones of the fluid passageways aredisposed in their entirety downstream of the axis of rotation of theclosure element when the same is in its fully open position, withcertain ones of the fluid passageways including portions or segmentswhich extend upstream and downstream of the axis of rotation when theclosure element is in its fully open position. The fluid passageways mayeach be tortuous, defining a series of turns which extend at generallyright angles relative to each other, with such tortuous fluidpassageways defining differing numbers of turns.

[0010] The impedance assembly is interfaced to the rotary closureelement such that flow through the valve assembly is applied initiallyto the fluid passageways having a greater number of turns when theclosure element is moved from its fully closed position toward its fullyopen position.

[0011] The impedance assembly comprises a series of plates which aresecured to each other in a stacked arrangement. Each of the platesincludes a plurality of flow passages (e.g., slots, openings, etc.)formed therein which collectively define the fluid passageways when theplates are stacked upon each other. The plates are stacked so as toextend along an axis which is generally perpendicular or normal to theaxis of the bore (i.e., extends in generally parallel relation to theaxis of rotation of the closure element). The surfaces of the platescollectively defining the inflow end of the impedance assembly arepreferably beveled so as to extend at an acute angle relative to theaxis of the bore. The surfaces of the plates collectively defining theoutflow end of the impedance assembly are preferably arcuately contouredso as to extend in substantially flush or continuous relation to theouter surface of the generally spherical closure element. The impedanceassembly may further comprise a layer of wire mesh material which isattached to and covers the inflow end thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These, as well as other features of the present invention, willbecome more apparent upon reference to the drawings wherein:

[0013]FIG. 1 is a cross-sectional view of an exemplary rotary valvehaving a closure element including an impedance assembly constructed inaccordance with a first embodiment of the present invention;

[0014]FIG. 2 is a front perspective view of the closure element andimpedance assembly of the first embodiment shown in FIG. 1;

[0015]FIG. 3 is a front elevational view of the closure element andimpedance assembly shown in FIG. 2;

[0016]FIG. 4 is a cross-sectional view of the closure element andimpedance assembly shown in FIGS. 2 and 3;

[0017]FIG. 5 is a front perspective view of the impedance assembly ofthe first embodiment;

[0018]FIG. 6 is a cutaway view of the impedance assembly of the firstembodiment illustrating the tortuous flow passageways defined thereby;

[0019]FIG. 7 is a cross-sectional view of the impedance assembly of thefirst embodiment;

[0020]FIG. 8 is an exploded view of the impedance assembly of the firstembodiment;

[0021]FIG. 9 is a front perspective view of a closure element includingan impedance assembly constructed in accordance with a second embodimentof the present invention;

[0022]FIG. 10 is a front elevational view of the closure element andimpedance assembly shown in FIG. 9;

[0023]FIG. 11 is a front perspective view of the impedance assembly ofthe second embodiment;

[0024]FIG. 12 is a front elevational view of the impedance assembly ofthe second embodiment;

[0025]FIG. 13 is a side-elevational view of the impedance assembly ofthe second embodiment;

[0026]FIG. 14 is a cross-sectional view of the impedance assembly of thesecond embodiment;

[0027]FIG. 15 is a front perspective view of a closure element includingan impedance assembly constructed in accordance with a third embodimentof the present invention;

[0028]FIG. 16 is a rear elevational view of the closure element andimpedance assembly shown in FIG. 15;

[0029]FIG. 17 is a front perspective view of the impedance assembly ofthe third embodiment;

[0030]FIG. 18 is a front elevational view of the impedance assembly ofthe third embodiment;

[0031]FIG. 19 is a cut-away perspective view of the impedance assemblyof the third embodiment illustrating the internal configuration of oneof the flow openings thereof;

[0032]FIG. 20 is an exploded view of the impedance assembly of the thirdembodiment in a pre-machined configuration;

[0033]FIG. 21 is a rear perspective view of the impedance assembly ofthe third embodiment in a partially machined configuration;

[0034]FIG. 22 is a cross-sectional view taken along line 22-22 of FIG.21;

[0035]FIG. 23 is an exploded view of one of the disk assemblies of theimpedance assembly of the third embodiment in a pre-machinedconfiguration;

[0036]FIG. 24 is a cross-sectional view taken from a front perspectiveof an exemplary rotary valve having a closure element including animpedance assembly constructed in accordance with a fourth embodiment ofthe present invention;

[0037]FIG. 25 is a cross-sectional view taken from a rear perspective ofthe rotary valve shown in FIG. 24 illustrating the impedance assembly ofthe fourth embodiment;

[0038]FIG. 26 is a cross-sectional view taken from a top perspective ofan exemplary rotary valve including the impedance assembly of the fourthembodiment, illustrating the closure element of the rotary valve in apartially open state;

[0039]FIG. 27 is a front elevational view of the closure element andimpedance assembly of the fourth embodiment;

[0040]FIG. 28 is a rear elevational view of the impedance assembly ofthe fourth embodiment;

[0041]FIG. 29 is a cross-sectional view of the closure element takenfrom a rear perspective, illustrating the impedance assembly of thefourth embodiment as mounted within the bore of the closure element;

[0042]FIG. 30 is an exploded view of the impedance assembly of thefourth embodiment in a pre-machined configuration;

[0043]FIG. 31 is a rear perspective view of the impedance assembly ofthe fourth embodiment in a pre-machined configuration;

[0044]FIG. 32 is an exploded view of one of the disk assemblies of theimpedance assembly of the fourth embodiment in a pre-machinedconfiguration; and

[0045]FIG. 33 is an exploded view similar to FIG. 32, illustrating oneof the disk assemblies of the impedance assembly of the fourthembodiment in a post-machined configuration.

DETAILED DESCRIPTION OF THE INVENTION

[0046] Referring now to the drawings wherein the showings are forpurposes of illustrating preferred embodiments of the present inventiononly, and not for purposes of limiting the same, FIG. 1 provides across-sectional view of a rotary valve 10 (e.g., a ball valve) having arotary closure element 12 (e.g., a ball) outfitted to include anon-board impedance assembly 14 constructed in accordance with a firstembodiment of the present invention. The valve 10 includes a housing 16which defines a flow path 18 extending axially therethrough. The closureelement 12 is operatively positioned within the flow path 18 of thehousing 16, and effectively segregates the flow path 18 into an inflowsection 20 and an outflow section 22. As best seen in FIG. 4, theclosure element 12 defines a bore 24 which extends axially therethrough.The formation of the bore 24 within the closure element 12 truncatesopposed ends of the closure element 12 which otherwise has a generallyspherical shape. In this regard, the bore 24 includes an inflow end 26and an outflow end 28 which are each defined by the closure element 12.

[0047] As further seen in FIG. 4, attached to the closure element 12 isa stem 30. The stem 30 extends radially from the closure element 12 insubstantially perpendicular relation to the axis of the bore 24. In thevalve 10, the closure element 12 is oriented within the flow path 18such that the axis of the bore 24 is selectively placeable into coaxialalignment with the axis of the flow path 18, with the axis of the stem30 extending in generally perpendicular relation to the axis of the flowpath 18. In this regard, the actuation of the closure element 12 to afully open position causes fluid flowing through the inflow section 20of the flow path 18 to flow into the inflow end 26 of the bore 24 alongthe axis thereof and subsequently into the outflow section 22 of theflow path 18 via the outflow end 28 of the bore 24. When actuated to itsfully closed position, the closure element 12 is rotated such that theaxis of the bore 24 extends in generally perpendicular relation to theaxis of the flow path 18, thus blocking the flow of fluid through theflow path 18 due to the impingement of the fluid flowing through theinflow section 20 against a side of the closure element 12.

[0048] As will be recognized, the closure element 12 may be rotated tovarious degrees of an open position between its fully open position andits fully closed position, i.e., the axis of the bore 24 may extend atan angle of between zero degrees and ninety degrees relative to the axisof the flow path 18. In FIG. 1, the closure element 12 is shown as beingrotated into an orientation wherein the axis of the bore 24 extends atan angle of approximately forty-five degrees relative to the axis of theflow path 18, thus placing the valve 10 into a partially open state.Those of ordinary skill in the art will recognize that the structuralattributes of the valve 10 are exemplary only, and that the impedanceassembly 14 of the first embodiment of the present invention as will bedescribed in more detail below may be employed in a multiplicity ofdifferently configured rotary valves.

[0049] Referring now to FIGS. 2-8, there is shown the impedance assembly14 which is constructed in accordance with the first embodiment of thepresent invention. As indicated above, the impedance assembly 14 iscarried by the closure element 12, and more particularly is operativelypositioned within the bore 24 in a manner which will be described inmore detail below. As will also be discussed below, the structuralattributes of the impedance assembly 14 allow the same to be retrofittedto the closure element 12 of an existing valve 10, or provided as anoriginal component thereof.

[0050] The impedance assembly 14 comprises a cylindrically configuredmain feeder cap 32 which, in a preliminary, un-machined states, definesa generally planar outer surface 34 and an opposed, generally planarinner surface. Disposed within the main feeder cap 32 are a plurality ofmain feeder passages 36 which extend therethrough. The main feederpassages 36 are segregated into various sets, with one set of the mainfeeder passages 36 having elongate, slot-like configurations and beingarranged in an arcuate pattern, and other sets of the main feederpassages 38 each having generally circular configurations. As seen inFIGS. 2 and 3, two sets of the circularly configured main feederpassages 36 are disposed at respective ones of the opposed ends of thearcuate set of elongate main feeder passages 36. Also disposed withinthe main feeder cap 32 is an enlarged opening 37.

[0051] As best seen in FIGS. 7 and 8, in addition to the main feeder cap32, the impedance assembly 14 includes a secondary feeder cap 38 whichhas a circular, plate-like configuration and is abutted against theinner surface of the main feeder cap 32. Disposed within the feeder cap38 are a plurality of feeder cap passages 40 and an opening 41 which hasthe same general profile or shape as the opening 37 of the main feedercap 32. The impedance assembly 14 further comprises a plurality ofcircularly configured expansion plates 42, each of which includes aplurality of expansion passages 44 formed therein. In addition to theexpansion passages 44, each expansion plate 42 includes an opening 45disposed therein which has the same general shape or profile as theabove-described openings 37, 41. Also included in the impedance assembly14 are a plurality of circularly configured spacer plates 46 which areinterleaved between respective pairs of the expansion plates 42 and eachinclude a plurality of spacer passages 48 therein. In addition to thespacer passages 48, each expansion plate 42 includes an opening 49disposed therein which has the same general shape or profile as theopenings 37, 41, 45. Finally, the impedance assembly 14 includes acircularly configured exit plate 50 which itself includes a plurality ofexit passages 52 disposed therein. The exit plate 50 also includes anopening 53 disposed therein which has the same general shape or profileas the openings 37, 41, 45, 49.

[0052] In the impedance assembly 14, the main feeder cap 32, feeder cap38, and expansion, spacer and exit plates 42, 46, 50 are assembled in astacked arrangement, and are preferably of equal outer diameters. Asindicated above, the feeder cap 38 is abutted against the inner surfaceof the main feeder cap 36, with the expansion and spacer plates 42, 46being stacked in succession upon the feeder cap 38. The uppermostexpansion plate 42 is abutted against that surface of the feeder cap 38opposite that abutted against the inner surface of the main feeder cap32. The exit plate 50 is abutted against the lowermost expansion plate42. The main feeder cap 32, feeder cap 38, and expansion, spacer andexit plates 42, 46, 50 are preferably maintained in a stackedarrangement via brazed connections, though other attachment methods maybe employed as an alternative.

[0053] When the impedance assembly 14 is initially assembled, the mainfeeder cap 32, feeder cap 38, and expansion, spacer and exit plates 42,46, 50 are stacked upon each other such that the main feeder passages36, feeder cap passages 40, expansion passages 44, spacer passages 48,and exit passages 52 are oriented relative to each other in a mannercollectively defining a plurality of tortuous passageways 54 and aplurality of generally straight passageways 56 which each extend throughthe impedance assembly 14. Similar to the main feeder passages 36, thefeeder cap passages 40 of the feeder cap 48 include those which have anelongate, slot-like configuration and are arranged in arcuate patterns,and those which have a generally circular configuration. The expansionpassages 44 of each of the expansion plates 42, the spacer passages 48of each of the spacer plates 46, and the exit passages 52 of the exitplate 50 are also provided in both elongate and circular configurations.

[0054] In the impedance assembly 14, the main feeder cap 32, feeder cap38, and expansion, spacer and exit plates 42, 46, 50 are stacked uponeach other such that the circularly configured passages thereof aredisposed in coaxially aligned sets. Each coaxially aligned set ofcircularly configured passages collectively define a respective one ofthe straight passageways 56 of the impedance assembly 14. The elongatepassages of the main feeder cap 32, feeder cap 38, and expansion, spacerand exit plates 42, 46, 50 are also arranged in sets wherein thepassages of each set are only partially aligned with each other (i.e.,only partially overlap) such that each set of the partially alignedelongate passages collectively define a respective one of the tortuouspassageways 54.

[0055] As seen in FIG. 6, the tortuous passageways 54 of the impedanceassembly 14 are not formed to provide uniform noise or energyattenuation characteristics. In this regard, those tortuous passageways54 partially defined by the main feeder passages 36 disposed in theapproximate center of the arcuate arrangement thereof provide thehighest level of energy attenuation capability (i.e., define thegreatest number of turns). The noise or energy attenuating capabilitiesof the remaining tortuous passageways 54 progressively decrease (i.e.,the number of turns defined by the passageways 54 is reduced) as theyapproach respective ones of the opposed ends of the arcuate arrangementof main feeder passages 36. As such, those tortuous passageways 54disposed closest to each of the sets of circular main feeder passages 36at the opposed ends of the elongate main feeder passages 36 define theleast number of turns, and hence provide a level of energy attenuationexceeding only that of the straight passageways 56.

[0056] As is further seen in FIG. 8, when the impedance assembly 14 isinitially assembled, the openings 37, 41, 45, 49 and 53 are also alignedwith each other and collectively define a flow opening 58 which extendsthrough the impedance assembly 14. The remaining portions of the mainfeeder cap 32, feeder cap 38, and expansion, spacer and exit plates 42,46, 50 collectively define an annular outer wall of the impedanceassembly 14 and a circumferential section which spans in the range offrom about ninety degrees to about one hundred twenty degrees andincludes each of the tortuous passageways 54 and straight passageways 56extending therethrough. As such, the flow opening 58 collectivelydefined by the openings 37, 41, 45, 49, 53 spans in the range from about240 degrees to about 270 degrees. Prior to the assembly of the impedanceassembly 14, the outer surface 34 of the main feeder cap 32 is machinedso as to provide the same with an arcuate, generally convexconfiguration. The pre-machining thickness of the main feeder cap 32allows for the completion of this machining operation.

[0057] Referring now to FIGS. 2-4, upon the fabrication of the impedanceassembly 14, the same is advanced into the bore 24 of the closureassembly 12. It is contemplated that the impedance assembly 14 may be“shrink-fit” into the closure element 12. However, those of ordinaryskill in the art will recognize that alternative attachment methods maybe employed to facilitate the interface of the impedance assembly 14 tothe closure element 12. In any such attachment method, it is preferredthat the inner surface of the closure element 12 defining the bore 24thereof be formed to include an annular shoulder 60 which serves as anabutment or stop surface for the impedance assembly 14. In this regard,the shoulder 60 is oriented such that the abutment of the exit plate 50thereagainst causes the arcuate outer surface 34 of the main feeder cap32 to extend in a flush or continuous relationship with the outersurface of the closure element 12 at the inflow end 26 of the bore 24.In this regard, it is contemplated that the outer surface 34 of the mainfeeder cap 32 will be machined such that the contour is complementary tothat of the outer surface of the closure element 12.

[0058] Due to the configuration of the impedance assembly 14, the numberof tortuous and straight passageways 54, 56 exposed to flow along theaxis of the flow path 18 varies as the closure element 12 is rotatedfrom its fully closed position toward its fully open position. In thisregard, when the closure element 12 is initially cracked open, fluidwill flow only into those tortuous passageways 54 imparting the highestlevel of energy attenuation, i.e., only those tortuous passageways 54partially defined by the main feeder passages 36 disposed in theapproximate center of the arcuate arrangement thereof are exposed to thefluid flow. As the opening of the closure element 12 progresses, theremaining tortuous passageways 54 of lesser energy attenuatingcapability are progressively exposed to the fluid flow. Thus, the numberof tortuous passageways 54 exposed to fluid flow progressively increasesas the closure element 12 is rotated toward its fully open position. Dueto their orientations relative to the tortuous passageways 54, thestraight passageways 56 are exposed to fluid flow once flow hascommenced through virtually all of the tortuous passageways 54. Thecontinued rotation of the closure element 12 toward its fully openposition then allows fluid to flow through the flow opening 58 definedby the impedance assembly 14 in an unrestricted manner. When the closureelement 12 is ultimately rotated to its fully open position, a portionof the fluid flow continues to flow through the tortuous and straightpassageways 54, 56, with the majority of the fluid flow passing throughthe flow opening 58. Thus, the impedance assembly 14 provides thebenefits of those utilized in linear valve arrangements, yet impartsthose benefits to the rotary closure element 12 of the valve 10.

[0059] Referring now to FIGS. 9-14, there is shown an impedance assembly62 which is constructed in accordance with a second embodiment of thepresent invention. Like the impedance assembly 14 of the firstembodiment described above, the impedance assembly 62 is carried by theclosure element 12, and more particularly is operatively positionedwithin the bore 24 in a manner which will be described in more detailbelow. The structural attributes of the impedance assembly 62 also allowthe same to be retrofitted to the closure element 12 of an existingvalve 10, or provided as an original component thereof.

[0060] The impedance assembly 62 comprises a feeder cap 64 which ismachined so as to define an arcuate, convex outer surface 66. Disposedwithin the feeder cap 64 are a plurality of feeder passages 68 whichextend therethrough. Each of the feeder passages 68 has a generallyrectangular cross-sectional configuration, though those of ordinaryskill in the art will recognize that the present invention is notintended to be limited to any particular shape for the feeder passages68. Also disposed within the feeder cap 64 is a generallycrescent-shaped opening 70.

[0061] As best seen in FIG. 13, in addition to the feeder cap 64, theimpedance assembly 62 includes a plurality of circularly configuredimpedance plates 72. The impedance plates 72 each include a plurality ofimpedance passages formed therein. In addition to the impedancepassages, each of the impedance plates 72 includes an opening formedtherein which has the same general shape or profile of the opening 70formed within the feeder cap 64. The impedance plates 72 are stackedupon each other, with an upper most one of the impedance plates 72 beingabutted against the inner surface of the feeder cap 64. In addition tothe feeder cap 64 and impedance plates 72, the impedance assembly 62includes a plurality of exit passages disposed therein. In addition tothe exit passages, the exit plate 74 includes an opening disposedtherein which has the same general shape or profile as the opening 70 ofthe feeder cap 64 and the opening within each of the impedance plates72.

[0062] In the impedance assembly 62, the feeder cap 64, impedance plates72 and exit plate 74 are assembled in a stacked arrangement, and arepreferably of equal outer diameters. As indicated above, the upper mostimpedance plate 72 within the stack is abutted against the inner surfaceof the feeder cap 64, with the impedance plates 72 being stacked insuccession upon the feeder cap 64. The exit plate 74 is abutted againstthe lower most impedance plate 72. The feeder cap 64, impedance plates72 and exit plate 74 are preferably maintained in a stacked arrangementvia brazed connections, though other attachment methods may be employedas an alternative.

[0063] When the impedance assembly 62 is initially assembled, the feedercap 64 and impedance and exit plates 72, 74 are stacked upon each othersuch that the feeder passages 68, impedance passages and exit passagesare oriented relative to each other in a manner collectively defining aplurality of tortuous passageways 76 which are best shown in FIG. 14. Asis apparent from FIG. 14, some of the tortuous passageways 76 extendlongitudinally through the entire length of the impedance assembly 62(i.e., terminate at the exit plate 74), with some of the tortuouspassageways 76 terminating at a side surface collectively defined by theperipheral edges of the impedance plates 72. When the feeder cap 64 andimpedance and exit plates 72, 74 are stacked upon each other, the feederpassages 68, impedance passages, and exit passages are arranged in setswherein certain passages of each set are coaxially aligned with eachother in a longitudinal direction, with other passages of the same setbeing laterally or radially aligned with each other, or only partiallyaligned in a longitudinal or lateral direction (i.e., only partiallyoverlapping) such that each set of the passages collectively define arespective one of the tortuous passageways 76.

[0064] In addition to the feeder passages 68, impedance passages andexit passages being aligned in sets to collectively define the tortuouspassageways 76, the opening 70 within the feeder cap 64 and openingswithin the impedance plates 72 and exit plate 74 are also aligned so asto collectively define a flow opening 78 which extends longitudinallythrough the impedance assembly 62. As is further seen in FIG. 14, thetortuous passageways 76 of the impedance assembly 62 are not formed toprovide uniform noise or energy attenuation characteristics. In thisregard, those tortuous passageways 76 disposed furthest from the flowopening 78 are configured to provide the highest level of energyattenuation capability (i.e., define the greatest number of turns). Thenoise or energy attenuating capabilities of the remaining tortuouspassageways 76 progressively decrease (i.e., the number of turns definedby the passageways 76 is reduced) as they approach the flow opening 78.Those tortuous passageways 76 having the highest energy attenuatingcapabilities (defining the greatest number of turns) each terminate atthe exit plate 74. Those tortuous passageways 76 of lesser energyattenuation capability terminate at the side surface collectively defineby the impedance plates 72, and hence facilitate outflow directly intothe flow opening 78.

[0065] Upon the fabrication of the impedance assembly 62, the same isadvanced into the bore 24 of the closure element 12. It is contemplatedthat the impedance assembly 62 may be “shrink-fit” into the closureelement 12. However, those of ordinary skill in the art will recognizethat alternative attachment methods may be employed to facilitate theinterface of the impedance assembly 62 to the closure element 12. Whenthe impedance assembly 62 is properly interfaced to the closure element12, the arcuate outer surface 66 of the feeder cap 64 will extend in aflush or continuous relationship with the outer surface of the closureelement 12 at the inflow end 26 of the bore 24. In this regard, it iscontemplated that the outer surface 66 of the feeder cap 64 will bemachined such that its contour is complimentary to that of the outersurface of the closure element 12.

[0066] Due to the configuration of the impedance assembly 62, the numberof tortuous passageways 76 exposed to flow along the axis of the flowpath 18 varies as the closure element 12 is rotated from its fullyclosed position toward its fully open position. In this regard, when theclosure element 12 is initially cracked open, fluid will flow only intothose tortuous passageways 76 imparting the highest level of energyattenuation. As the opening of the closure element 12 progresses, theremaining tortuous passageways 76 of lesser energy attenuatingcapability are progressively exposed to the fluid flow. Thus, the numberof tortuous passageways 76 exposed to fluid flow progressively increasesas the closure element 12 is rotated toward its fully open position. Thecontinued rotation of the closure element 12 toward its fully openposition then allows fluid to flow through the flow opening 78 definedby the impedance assembly 62 in an unrestricted manner. When the closureelement 12 is ultimately rotated to its fully open position, a portionof the fluid flow continues to flow through the tortuous passageways 76,with fluid flow also passing through the flow opening 78. Thus, like theimpedance assembly 14 described above, the impedance assembly 64 of thesecond embodiment provides the benefits of those utilized in linearvalve arrangements, yet imparts those benefits to the rotary closureelement 12 of the valve 10.

[0067] Referring now to FIGS. 15-23, there is shown an impedanceassembly 80 constructed in accordance with a third embodiment of thepresent invention. Like the impedance assemblies 14, 62 of the first andsecond embodiments described above, the impedance assembly 80 of thethird embodiment is carried by the closure element 12, and moreparticularly is operatively positioned within the bore 24 in a mannerwhich will be described in more detail below. The structural attributesof the impedance assembly 80 also allow the same to be retrofitted tothe closure element 12 of an existing valve 10, or provided as anoriginal component thereof.

[0068] Referring now to FIGS. 20-22, the impedance assembly 80 comprisesan upper cap 82 which, in a preliminary, un-machined state, has agenerally rectangular configuration defining an inlet side surface 82 aand an outlet side surface 82 b. In this regard, the inlet and outletside surfaces 82 a, 82 b are defined by respective ones of thelongitudinal sides of the rectangularly configured upper cap 82. Inaddition to the upper cap 82, the impedance assembly 80 includes aplurality of impedance plate assemblies 84 which are maintained in astacked arrangement, and are best shown in FIGS. 20 and 23. Eachimpedance plate assembly 84 comprises a rectangularly configuredseparator plate 86, a rectangularly configured first impedance plate 88,and a rectangularly configured second impedance plate 90. Formed withinthe first impedance plate 88 are a plurality of elongate slots labeled92 a-92 e, respectively. Also formed within the first impedance plate 88adjacent the inner ends of the slots 92 a-92 c are various openings 94,some of which are formed within one of the longitudinal peripheral edgesegments of the first impedance plate 88. Similarly, formed within thesecond impedance plate 90 are a plurality of openings 96, some of whichalso are formed within one of the longitudinal peripheral edge segmentsof the second impedance plate 90.

[0069] Within each impedance plate assembly 84, the separator plate 86,first impedance plate 88, and second impedance plate 90 are maintainedin a stacked arrangement. In this regard, the length and widthdimensions of the separator plate 86, first impedance plate 88 andsecond impedance plate 90 are preferably substantially equal, such thatthe longitudinal and lateral peripheral edge segments thereof aresubstantially flush when the plates 86, 88, 90 are stacked. The stackingis completed such that the openings 96 of the second impedance plate 90partially overlap corresponding openings 94 and slots 92 a-e of thefirst impedance plate 88. The separator plate 86 is attached to one sideor face of the second impedance plate 90 such that the second impedanceplate 90 is disposed or sandwiched between the separator plate 86 andthe first impedance plate 88.

[0070] As is further seen in FIG. 20, within the impedance assembly 80,the impedance plate assemblies 84 are stacked upon the upper cap 82. Theuppermost impedance plate assembly 84 of the impedance assembly 80 doesnot include the separator plate 86, with the second impedance plate 90thereof being abutted directly against the bottom surface of the uppercap 82. For each successively stacked impedance plate assembly 84, theseparator plate 86 of each such impedance plate assembly 84 is abuttedagainst the first impedance plate 88 of the impedance plate assembly 84immediately above it.

[0071] In addition to the upper cap 82 and impedance plate assemblies84, the impedance assembly 80 includes a lower cap 90 which, like theupper cap 82, has a generally rectangular configuration in itspreliminary, un-machined state, and defines an inlet side surface 98 aand an outlet side surface 98 b. In the impedance assembly 80, the topsurface of the lower cap 98 is abutted against the first impedance plate88 of the lowermost impedance plate assembly 84. As seen in FIGS. 20-22,the length and width dimensions of the upper and lower caps 82, 98 arealso substantially equal to those of the plates 86, 88, 90, with thelongitudinal and lateral sides of the upper and lower caps 82, 98 beingsubstantially flush with the longitudinal and lateral peripheral edgesegments of the plates 86, 88, 90, i.e., the inlet side surfaces 82 a,98 a and outlet side surfaces 82 b, 98 b are substantially flush orcontinuous with respective ones of the longitudinal peripheral edgesegments of the plates 86, 88, 90.

[0072] As is seen in FIGS. 20 and 23, the upper and lower caps 82, 98and plates 86, 88, 90 each preferably include an alignment or registryaperture 100 disposed within a corner region thereof. The alignmentapertures 100 are included in prescribed corner regions of the upper andlower caps 82, 98 and plates 86, 88, 90, and are adapted to facilitate aproper registry between such components in the stacking thereof. In thisregard, the apertures 100 are brought into coaxial alignment with eachother, and are adapted to receive a retention pin which, when advancedthereinto, assists in maintaining the upper and lower caps 82, 98 andplates 86, 88, 90 in a proper, stacked registry.

[0073] In the impedance assembly 80, the stacking of the upper cap 82,impedance plate assemblies 84, and lower cap 98 occurs in a mannerwherein the slots 92 a-e terminate at the longitudinal peripheral edgesegment of the first impedance plate 88 which extends along the inletside surfaces 82 a, 98 a of the upper and lower caps 82, 98, and theopenings 94, 96 are disposed adjacent to or formed within thelongitudinal peripheral edge segments of the first and second impedanceplates 88, 90 which extend along the outlet side surfaces 82 b, 98 b ofthe upper and lower caps 82, 98. In FIGS. 20 and 21, the impedance plateassemblies 84 are viewed from the rear perspective, and are shown from afront perspective in FIG. 23. The exploded view from the frontperspective in FIG. 23 demonstrates that each impedance plate assembly84 defines a plurality of tortuous passageways which extend between thelongitudinal peripheral edge segments of the plates 86, 88, 90 in spacedrelation to each other.

[0074] Due to the arrangement of the openings 94, 96 within the firstand second impedance plates 88, 90, the tortuous passageway partiallydefined by the slot 92 a includes a total of eight turns, with thetortuous passageway partially defined by the slot 92 b defining a totalof six turns, the tortuous passageway partially defined by the slot 92 cdefining a total of four turns, and the tortuous passageways partiallydefined by the slots 92 d, 92 e each defining a total of two turns.Thus, the number of turns defined by the tortuous passageways decreasesas the passageways progress from left to right viewed from the frontperspective shown in FIG. 23. Those of ordinary skill in the art willrecognize that the number of turns defined by the tortuous passagewaysas described above is exemplary only, and that slots and openings may beformed in the impedance plates 88, 90 as needed to effectuate theimplementation of differing numbers of turns. Moreover, as is seen inFIGS. 20 and 21, the distance separating the slots 92 a-e and openings94, 96 from each other and from the lateral peripheral edge segments ofrespective ones of the first and second impedance plates 88, 90 is notperfectly uniform within all of the impedance plate assemblies 84.Rather, these separation distances are varied as needed to arrange thetortuous passageways in sets wherein the tortuous passageways of eachset define equal numbers of turns but extend in a generally arcuatepattern.

[0075] In the impedance assembly 80 of the third embodiment, theimpedance plate assemblies 84 and upper and lower caps 82, 98 arepreferably maintained in their stacked arrangement via brazedconnections, though other attachment methods may be employed as analternative. Upon the stacking of the upper and lower caps 82, 98 andimpedance plate assemblies 84 in the above-described manner, a top flowopening 102 is formed into the upper cap 82 and extends between theinlet and outlet side surfaces 82 a, 82 b thereof. Similarly, a bottomflow opening 104 is formed into the lower cap 98 and extends between theinlet and outlet side surfaces 98 a, 98 b thereof. The top and bottomflow openings 102, 104 may each be formed within respective ones of theupper and lower caps 82, 98 via a wire EDM process. As seen in FIG. 19,preferably disposed within the top flow opening 102 is a first plate 106and a second plate 108 which are each attached (e.g., welded) to theupper cap 82. The first plate 106 and second plate 108 are arrangedwithin the top flow opening 102 relative to each other such that the topflow opening 102 does not define a straight flow path, but ratherdefines a tortuous flow path defining two turns. Those of ordinary skillin the art will recognize that differing numbers of plates may bedisposed within the top flow opening 102 in differing arrangements asneeded to facilitate the creation of differing numbers of turns, or thatno plates at all need be included within the top flow opening 102. Inthe impedance assembly 80, the first and second plates 106, 108 are alsodisposed within the bottom flow opening 104 in the same arrangementshown in FIG. 19A so as to define a tortuous passageway having two turnstherein. It will further be recognized that the top and bottom flowopenings 102, 104 may each have a shape differing from that shown in thefigures (e.g., tear drop, round, triangular, etc.) to give the trim aspecific flow curve characteristic.

[0076] After the first and second plates 106, 108 have been insertedinto each of the top and bottom flow openings 102, 104, the upper andlower caps 82, 98 and impedance plate assemblies 84 of the impedanceassembly are machined so as to impart to the stacked arrangement thegenerally elliptical profile shown in FIGS. 17 and 18. As such, theimpedance assembly 80 includes an arcuate outer surface 110 collectivelydefined by portions of the upper and lower caps 82, 98 and impedanceplate assemblies 84, and an arcuate inner surface 112 which is itselfcollectively defined by portions of the upper and lower caps 82, 98 andimpedance plate assemblies 84, and an arcuate inner surface 112 which isitself collectively defined by portions of the upper and lower caps 82,98 and impedance plate assemblies 84. The outer and inner surfaces 110,112 meet each other at a top apex 114 defined by the upper cap 82 anddisposed adjacent the top flow opening 102, and a bottom apex 116defined by the lower cap 98 and disposed adjacent the bottom flowopening 104. Within the machined impedance assembly 80, the tortuouspassageways of greatest noise or energy attenuating capability (i.e.,the tortuous passageways defining the greatest number of turns) aredisposed closest to the outer surface 110, with the number of turns (andhence the noise attenuating capability) of the tortuous passagewaysprogressively decreasing as they extend toward the inner surface 112.

[0077] Referring now to FIGS. 15 and 16, upon the impedance assembly 80being machined in the above-described manner, the same is advanced intothe bore 24 of the closure element 12. Such advancement is facilitatedin a manner wherein the outer surface 110 of the impedance assembly 80directly engages or abuts a portion of the inner surface of the closureelement 12 which defines the bore 24 thereof. In this regard, it iscontemplated that the contour of the outer surface 110 will becomplementary to that of the inner surface of the closure element 12defining the bore 24, such that the outer surface 110 may be broughtinto direct, flush engagement therewith. When properly positioned withinthe bore 24, a portion of the impedance assembly 80 protrudes from theinflow end 26 of the bore 24. Additionally, the inner surface 112 of theimpedance assembly 80 and a portion of the inner surface of the closureelement 12 defining the bore 24 thereof collectively define a generallycrescent-shaped flow opening 118. The thickness of the impedanceassembly 80 is substantially less than the length of the bore 24. Thus,when the impedance assembly 80 is properly positioned within the bore24, the impedance assembly 80 extends to a depth which is substantiallyshort of the rotational axis of the closure element 12 (i.e., the axisof the stem 30). It is contemplated that the impedance assembly 80 willbe welded in place within the bore 24 of the closure element 12, thoughthose of ordinary skill in the art will recognize that alternativeattachment methods may also be employed.

[0078] Once the impedance assembly 80 has been properly secured withinthe bore 24 of the closure element 12, that portion of the impedanceassembly 80 protruding from the inflow end 26 of the bore 24 issubjected to another machining operation which imparts an arcuatecontour or profile thereto as needed to cause the exposed outer inflowend of the impedance assembly 80 to be substantially flush or continuouswith the outer surface of the closure element 12 at the inflow end 26 ofthe bore 24. Stated another way, the impedance assembly 80 is machinedsuch that the contour of the outer inflow end thereof is complementaryto that of the outer surface of the closure element 12 as is best seenin FIG. 15.

[0079] Due to the configuration of the impedance assembly 80, the numberof tortuous passageways exposed to flow along the axis of the flow path18 varies as the closure element 12 is rotated from its fully closedposition toward its fully open position. In this regard, when theclosure element 12 is initially cracked open, fluid will flow only intothose tortuous passageways of the impedance assembly 80 imparting thehighest level of noise or energy attenuation. As the opening of theclosure element 12 progresses, the remaining tortuous passageways of theimpedance assembly 80 of lesser noise or energy attenuating capabilityare progressively exposed to the fluid flow. Thus, the number oftortuous passageways exposed to fluid flow progressively increases asthe closure element 12 is rotated toward its fully open position.

[0080] In addition to flowing through the tortuous passageways, thefluid flows into the top and bottom flow openings 102, 104 of theimpedance assembly 80 which, as indicated above, are also tortuous. Thecontinued rotation of the closure element 12 toward its fully openposition then allows fluid to flow through the flow opening 118 in anunrestricted manner. When the closure element 12 is ultimately rotatedto its fully open position, a portion of the fluid flow continues toflow through the tortuous passageways and top and bottom flow openings102, 104 of the impedance assembly concurrently with flow through theflow opening 118. Thus, like the impedance assemblies 14, 62 describedabove, the impedance assembly 80 of the third embodiment provides thebenefits of those utilized in linear valve arrangements, yet impartsthose benefits to the rotary closure element 12 of the valve 10.

[0081] One of the most significant structural distinctions between theimpedance assembly 80 of the third embodiment and the impedanceassemblies 14 and 62 of the first and second embodiments is that in theimpedance assembly 80 of the third embodiment, the impedance plateassemblies 84 are stacked in a direction which is generallyperpendicular or normal to the axis defined by the bore 24 of theclosure element 12. In contrast, the feeder caps and plates of theimpedance assemblies 14, 62 are stacked in a manner where they extendalong the axis defined by the bore 24 of the closure element 12.

[0082] Referring now to FIGS. 24-32, there is shown an impedanceassembly 200 constructed in accordance with a fourth embodiment of thepresent invention. The impedance assembly 200 of the fourth embodimentis also carried by the closure element 12 and, more particularly, isoperatively positioned within the bore 24 in a manner which will bedescribed in more detail below. The structural attributes of theimpedance assembly 200 also allow the same to be retrofitted to theclosure element 12 of an existing valve 10, or provided as an originalcomponent thereof.

[0083] The impedance assembly 200 comprises an upper cap 202 which, in apreliminary, un-machined state, has a generally rectangularconfiguration defining an inlet side surface 202 a and an outlet sidesurface 202 b. In addition to the upper cap 202, the impedance assembly200 includes a plurality of impedance plate assemblies 204 which aremaintained in a stacked arrangement, and are best shown in FIGS. 30-32.Each impedance plate assembly 204 comprises a separator plate 206, afirst impedance plate 208, and a second impedance plate 210. The plates206, 208, 210 each preferably have either a rectangular or squareconfiguration. Formed within the first impedance plate 208 are aplurality of openings 212. Similarly, formed within the second impedanceplate 210 are a plurality of openings 214. The openings 212, 214 are noteach of the same size, or arranged in the same patterns withinrespective ones of the first and second impedance plates 208, 210.Rather, the size and arrangement of the openings 212, 214 varies withincertain ones of the impedance plate assemblies 204 for reasons whichwill be discussed in more detail below.

[0084] Within each impedance plate assembly 204, the separator plate206, first impedance plate 208, and second impedance plate 210 aremaintained in a stacked arrangement. In this regard, the length andwidth dimensions of the separator plate 206, first impedance plate 208and second impedance plate 210 are preferably substantially equal, suchthat corresponding peripheral edge segments thereof are substantiallyflush when the plates 206, 208, 210 are stacked. The stacking iscompleted such that the openings 214 of the second impedance plate 210partially overlap one or more corresponding openings 212 of the firstimpedance plate 208. The separator plate 206 is attached to one side orface of the first impedance plate 208 such that the first impedanceplate 208 is disposed or sandwiched between the separator plate 206 andthe second impedance plate 210.

[0085] Within the impedance assembly 200, the impedance plate assemblies204 are stacked upon the upper cap 202. The second impedance plate 210of the uppermost impedance plate assembly 204 is abutted directlyagainst the bottom surface of the upper cap 202. For each successivelystacked impedance plate assembly 204, the second impedance plate 210 ofeach such impedance plate assembly 204 is abutted against the separatorplate 206 of the impedance plate assembly 204 immediately above it. Thelowermost impedance plate assembly 204 within the stack does not includethe separator plate 206, as will be described in more detail below.

[0086] In addition to the upper cap 202 and impedance plate assemblies204, the impedance assembly 200 of the fourth embodiment includes alower cap 216 which, like the upper cap 202, has a generally rectangularor square configuration in its preliminary, un-machined state, anddefines an inlet side surface 216 a and an outlet side surface 216 b. Inthe impedance assembly 200, the top surface of the lower cap 216 isabutted against the first impedance plate 208 of the lowermost impedanceplate assembly 204 which, as indicated above, does not include theseparator plate 206. The length and width dimensions of the upper andlower caps 202, 216 are substantially equal to those of the plates 206,208, 210 such that the peripheral sides of the upper and lower caps 202,216 are substantially flush with corresponding peripheral edge segmentsof the plates 206, 208, 210.

[0087] As is further seen in FIGS. 30-33, the upper and lower caps 202,216 and plates 206, 208, 210 each preferably include one or morealignment or registry apertures 218 disposed therein. The alignmentapertures 218 are adapted to facilitate a proper registry between theupper and lower caps 202, 216 and plates 206, 208, 210 in the stackingthereof. In this regard, the apertures 218 are brought into coaxialalignment with each other in a manner collectively defining twocoaxially aligned sets, each of which is adapted to receive a retentionpin. The advancement of such retention pins into the coaxially alignedsets of apertures 218 assists in maintaining the upper and lower caps202, 216 and plates 206, 208, 210 in a proper stacked registry.

[0088] The impedance plate assemblies 84 as stacked between the uppercap 202 and the lower cap 216 are shown in FIG. 31. As will be discussedin more detail below, the impedance plate assemblies 204 and the upperand lower caps 202, 216 are preferably maintained in their stackedarrangement via brazed connections, though other attachment methods maybe employed as an alternative. Subsequent to the stacking in theabove-described manner, the upper and lower caps 202, 216 andintermediate impedance plate assemblies 204 are preferably machined in amanner resulting in the upper and lower caps 202, 216 and the impedanceplate assemblies 204 collectively defining an inflow side or end 220 ofthe impedance assembly 200 which has an angled or beveled configuration,as best shown in FIG. 29. The inflow end 220 of the impedance assembly200 is preferably formed to extend at an angle of approximatelyforty-five degrees relative to the axis of the bore 24 of the closureelement 12 when the impedance assembly 200 is mounted therein.

[0089] In addition to being machined to define the beveled inflow end220, the upper and lower caps 202, 216 and intervening impedance plateassemblies 204 are further machined to collectively define an arcuatelycontoured, convex outflow side or end 222. The arcuate contour orprofile of the outflow end 222 is adapted to cause the same to besubstantially flush or continuous with the outer surface of the closureelement 12 at the outflow end 28 of the bore 24 when the impedanceassembly 200 is mounted therein. Stated another way, the impedanceassembly 200 is machined such that the contour of the outflow end 222thereof is complementary to that of the outer surface of the closureelement 12. The machining operation which imparts the arcuate contour orprofile to the outflow end 222 may occur prior or subsequent to themounting of the impedance assembly 200 into the bore 24 of the closureelement 12. However, the machining of the upper and lower caps 202, 216and impedance plate assemblies 204 as needed to facilitate the formationof the beveled inflow end 220 will necessarily occur prior to themounting of the impedance assembly 200 within the bore 24.

[0090] An exploded view of one of the impedance plate assemblies 204 ofthe impedance assembly 200, subsequent to the completion of themachining operations used to facilitate the formation of the inflow andoutflow ends 220, 222, is shown in FIG. 33. As shown in FIG. 33, themachining of the impedance plate assemblies 204 to form the beveledinflow end 220 results in certain ones of the openings 212, 214 withinthe first and second impedance plates 208, 210 each communicating withor extending to that edge segment of the corresponding plate 208, 210which partially defines the inflow end 220. Similarly, the machining ofthe impedance plate assemblies 204 to form the convex outflow end 222results in certain ones of the openings 212, 214 extending to thatperipheral segment of the corresponding plate 208, 210 which partiallydefines the outflow end 222. Certain ones of the openings 212, 214 ofthe first and second impedance plates 208, 210 are unaffected by themachining operations described above.

[0091] As is further seen in FIG. 33, as a result of the formation ofthe inflow and outflow ends 220, 222 in the above-described manner, eachof the plates 206, 208, 210 defines an opposed pair of side peripheraledge segments which extend between those peripheral edge segmentsdefining respective ones of the inflow and outflow ends 220, 222. Theside peripheral edge segments of each such pair are of differinglengths, with one being substantially shorter than the other. Inaddition to being machined to form the inflow and outflow ends 220, 222,the upper and lower caps 202, 216 and impedance plate assemblies 204 arefurther machined so as to impart to the stacked arrangement thegenerally elliptical profile best shown in FIGS. 27-29. As such, theimpedance assembly 200 includes an arcuate outer surface 224collectively defined by the side peripheral edge segments of the plates206, 208, 210 of shorter length and portions of the upper and lower caps202, 216. In addition to the outer surface 224, the impedance assembly200 defines an arcuate inner surface 226 which is collectively definedby the side peripheral edge segments of the plates 206, 208, 210 ofgreater length and portions of the upper and lower caps 202, 216. Theseouter and inner surfaces 224, 226 meet each other at a top apex 228defined by the upper cap 202, and a bottom apex 230 defined by the lowercap 216.

[0092] Due to the arrangement of the openings 212, 214 within the firstand second impedance plates 208, 210 of each impedance plate assembly204, each of the impedance plate assemblies 204 defines a plurality offluid passageways which are tortuous and extend between those peripheraledge segments partially defining respective ones of the inflow andoutflow ends 220, 222. These tortuous fluid passageways are disposed inspaced relation to each other and define differing numbers ofright-angle turns. More particularly, the number of turns defined by thetortuous fluid passageways decreases as the passages progress from theouter surface 224 to the inner surface 226 as viewed from the frontperspective shown in FIG. 27. Thus, those passageways defining thegreatest number of turns are disposed closest to the side peripheraledge segments of the plates 208, 210 of greatest length, with thosepassageways defining the least number of turns being disposed closest tothe side peripheral edge segments of the plates 208, 210 of shorterlength. As is further seen in FIG. 33, the arrangement of the openings212, 214 within the plates 208, 210 maximizes the surface area on eachof the plates 208, 210 which is available for use as a brazing area.Such increased brazing area enhances the integrity of the attachmentbetween the plates 206, 208, 210 within the impedance assembly 200.

[0093] As will be recognized, those tortuous passageways providing thegreatest noise or energy attenuating capability are those defining thegreatest number of turns which, as indicated above, are disposed closestto the outer surface 224. The number of turns (and hence the noiseattenuating capability) of the tortuous passageways progressivelydecreases as they extend toward the inner surface 226, as also indicatedabove.

[0094] Upon the impedance assembly 200 being machined in theabove-described manner, the same is advanced into the bore 24 of theclosure element 12. Such advancement is facilitated in a manner whereinthe outer surface 224 of the impedance assembly 200 directly engages orabuts a portion of the inner surface of the closure element 12 whichdefines the bore 24 thereof. In this regard, it is contemplated that thecontour of the outer surface 224 will be complementary to that of theinner surface of the closure element 12 defining the bore 24, such thatthe outer surface 224 may be brought into direct, flush engagementtherewith. When properly positioned within the bore 24, the outflow end222 of the impedance assembly 200 will extend to the outflow end 28 ofthe bore 24 in flush relation to the outer surface of the closureelement 12. However, if the outflow end 222 has not yet been machinedinto the impedance assembly 200, the same will be positioned within thebore 24 such that a portion thereof protrudes from the outflow end 28 ofthe bore 24, with the impedance assembly 200 thereafter being machinedso as to facilitate the formation of the outflow end 222 which extendsin continuous, flush relation to the outer surface of the closureelement 12.

[0095] The mounting of the impedance assembly 200 into the bore 24 ofthe closure element 12 is preferably accomplished through the use ofwelds. Upon such mounting, the inner surface 226 of the impedanceassembly 200 and a portion of the inner surface of the closure element12 defining the bore 24 thereof collectively define a generallycrescent-shaped flow opening 232. The thickness of the impedanceassembly 200, even at its thickest point, is substantially less than thelength of the bore 24. Thus, when the impedance assembly 200 is properlypositioned within the bore 24, the majority of the impedance assembly200 (and hence the majority of the tortuous fluid passageways definedthereby) extends between the rotational axis of the closure element 12(i.e., the axis of the stem 30) and the outflow end 28 of the bore 24.However, as seen in FIG. 26, portions or segments of those fluidpassageways defining the greatest number of turns (i.e., thosepassageways disposed closest to the outer surface 224) extend upstreamof the rotational axis of the closure element 12 (i.e., between the axisof the stem 30 and the inflow end 26 of the bore 24). However, those ofordinary skill in the art will recognize that the impedance assembly 200may be sized such that the entirety thereof is disposed downstream ofthe rotational axis of the closure element 12.

[0096] Due to the configuration of the impedance assembly 200, thenumber of tortuous passageways directly impinged by flow along the axisof the flow path 18 varies as the closure element 12 is rotated from itsfully closed position toward its fully open position. In this regard, asseen in FIG. 26, when the closure element 12 is initially cracked open,the fluid flow into the bore 24 directly impinges only those tortuouspassageways of the impedance assembly 200 imparting the highest level ofnoise or energy attenuation. As the opening of the closure element 12progresses, the remaining tortuous passageways of the impedance assembly200 of lesser noise or energy attenuating capability are progressivelydirectly impinged by the flow of fluid into the bore 24 of the closureelement 12. Thus, the number of tortuous passageways directly impingedby fluid flow into the bore 24 progressively increases as the closureelement 12 is rotated toward its fully open position. The continuedrotation of the closure element 12 toward its fully open position thenallows fluid to flow through the flow opening 232 in an unrestrictedmanner. When the closure element 12 is ultimately rotated to its fullyopen position, a portion of the fluid flow continues to flow through thetortuous passageways concurrently with flow through the flow opening232.

[0097] In the impedance assembly 200 of the fourth embodiment, theimpedance plate assemblies 204 are stacked in a direction which isgenerally perpendicular or normal to the axis defined by the bore 24 ofthe closure element 12. Advantageously, by orienting the inflow end 220of the impedance assembly 200 downstream of the inflow end 26 of thebore 24, any solid “trash” particles which become trapped in the inflowend 220 of the impedance assembly 200 are downstream of the soft frontseat 234 of the valve 10. As a result, the susceptibility of the frontseat 234 to being cut or torn by such trash particles during rotation ofthe closure element 12 between its fully open and fully closed positionsis eliminated. As will be recognized, in typical valve construction, itis preferred that the front seat 234 be fabricated from a soft materialas is adapted to facilitate the creation of a bubble-tight seal (e.g., aClass 6 shut-off). As indicated above, the location of the impedanceassembly 200 at the back of the closure element 12 eliminates thesusceptibility to the tearing of the soft front seat 234 due to thesolid trash particles being collected inside the bore 24 of the closureelement 12, far away from the front seat 234. Thus, the soft upstreamfront seat 234 need not be used for throttling, and may be used only asa primary shut-off seal which is its main function in a regular trunnionball valve. As a result, the downstream back seat 236 may be convertedto a metal seal used strictly for throttling purposes.

[0098] In addition to the aforementioned advantages attributable to theplacement of the impedance assembly 200 to the back of the bore 24within the closure element 12, the formation of the angled inflow end220 of the impedance assembly 200 (which is located within the bore 24)provides an optimal angle for trash deflection. In this regard, solidparticles will tend to be deflected toward the flow opening 232, whichprovides a “self-flushing” feature. It is contemplated that theimpedance assembly 200 may be provided with a layer 238 of wire meshmaterial which is attached to and completely covers the inflow end 220(i.e., the deflection face). The wire mesh layer 238 covering the inflowend 220 further protects against any clogging of the tortuous fluidpassageways, while further enhancing the noise attenuation capabilitiesof the impedance assembly 200. It is contemplated that several layers238 of wire mesh material (as opposed to a single layer 238) may bestacked upon the inflow end 220. In this regard, the wire mesh layer(s)238, in addition to keeping trash out of the tortuous fluid passageways,can be used as a noise attenuation barrier, with differing levels ofnoise reduction being achievable based on the number of layers 238 ofwire mesh material stacked upon the inflow end 220. The increasedbrazing area on the plates 206, 208, 210, as described above, providesan increase in brazing quality and a reduced potential for any of theplates 206, 208, 210 from breaking off of the stack. Additionally, theoverall configuration of the impedance assembly 200 provides for the useof additional stringer welds to facilitate the attachment thereof to theclosure element 12.

[0099] Additional modifications and improvements of the presentinvention may also be apparent to those of ordinary skill in the art.For example, as shown in the accompanying figures, the impedanceassembly 80 of the third embodiment is formed to have a generallyelliptical configuration, which results in the flow opening 118 beinggenerally crescent-shaped when the impedance assembly 80 is advancedinto the bore 24 of the closure element 12. In this regard, theimpedance assembly 80 may be formed to have alternative shapes as wouldcause the flow opening 118 to have a shape other than a crescent shape.More particularly, the shape of the flow opening 118 can be varied bymodifying the shape of the impedance assembly 80, with the shape of theflow opening 118 being selected to provide a desired flow curvecharacteristic. The same holds true for the shape of the impedanceassembly 200 and resultant shape of the flow opening 232. Additionally,it is contemplated that the impedance assembly 200 may be sized andconfigured so as to completely cover or extend across the bore 24 of theclosure element 12, i.e., the flow opening 232 is not defined. Thus, theparticular combination of parts described and illustrated herein isintended to represent only certain embodiments of the present invention,and is not intended to serve as limitations of alternative deviceswithin the spirit and scope of the invention.

1. A valve assembly, comprising: a rotary closure element defining anaxis of rotation and selectively movable between a fully open positionand a fully closed position; an impedance assembly mounted to andmovable with the rotary closure element, the impedance assembly definingan inflow end and an outflow end, and comprising: a plurality of fluidpassageways extending from the inflow end to the outflow end; theimpedance assembly and the closure element collectively defining a flowopening which extends from the inflow end to the outflow end; the fluidpassageways and the flow opening being oriented relative to each othersuch that a portion of a flow through the valve assembly is directedinto the fluid passageways and a portion of the flow is directed throughthe flow opening when the closure element is in the fully open position.2. The valve assembly of claim 1 wherein the impedance assembly isconfigured and oriented relative to the closure element such that thefluid passageways are each downstream of the axis of rotation when theclosure element is in the fully open position.
 3. The valve assembly ofclaim 2 wherein the impedance assembly is configured and orientedrelative to the closure element such that certain ones of the fluidpassageways include portions which are upstream of the axis of rotationwhen the closure element is in the fully open position.
 4. The valveassembly of claim 1 wherein: at least some of the fluid passageways aretortuous and define a series of turns which extend at generally rightangles relative to each other; and the tortuous fluid passageways of theimpedance assembly define differing numbers of turns.
 5. The valveassembly of claim 4 wherein the impedance assembly is mounted to theclosure element such that flow is applied initially to the tortuouspassageways having a greater number of turns when the closure element ismoved from the fully closed position toward the fully open position. 6.The impedance assembly of claim 1 wherein the inflow end has a beveledconfiguration.
 7. The impedance assembly of claim 6 further comprising alayer of wire mesh attached to the impedance assembly and covering theinflow end thereof.
 8. The valve assembly of claim 1 wherein: theimpedance assembly comprises a plurality of impedance plate assembliessecured to each other in a stacked arrangement along an axis which isgenerally parallel to the axis of rotation; and each of the impedanceplate assemblies includes a plurality of openings formed therein whichcollectively define the fluid passageways when the impedance plateassemblies are stacked upon each other.
 9. The valve assembly of claim 8wherein each of the impedance plate assemblies comprises: a separatorplate; a first impedance plate having a plurality of slots and openingsformed therein; and a second impedance plate having a plurality of slotsand openings formed therein; the separator, first and second impedanceplates being stacked upon each other such that the separator and firstimpedance plates, with the slots and openings of the first and secondimpedance plates collectively defining the fluid passageways.
 10. Thevalve assembly of claim 9 wherein: the closure element defines anarcuate outer surface; the impedance plate assemblies are configured ina manner wherein the outflow end of the impedance assembly is arcuatelycontoured; and the impedance assembly is mounted to the closure elementsuch that the arcuate outflow end of the impedance assembly issubstantially continuous with the outer surface of the closure element.11. The valve assembly of claim 10 wherein the impedance plateassemblies are configured in a manner wherein the inflow end of theimpedance assembly has a beveled configuration.
 12. The valve assemblyof claim 8 wherein the impedance assembly further comprises: an uppercap; and a lower cap; the impedance plate assemblies being stackedbetween the upper and lower caps.
 13. An impedance assembly for retrofitattachment to a rotary closure element defining an axis of rotation andselectively movable between a fully open position and a fully closedposition, the impedance assembly comprising: a plurality of impedanceplate assemblies secured to each other in a stacked arrangement suchthat the impedance plate assemblies collectively define an inflow endand an outflow end of the impedance assembly; each of the impedanceplate assemblies including a plurality of openings formed therein whichcollectively define a plurality of fluid passageways extending from theinflow end to the outflow end when the impedance plate assemblies arestacked upon each other.
 14. The impedance assembly of claim 13 whereineach of the impedance plate assemblies comprises: a separator plate; afirst impedance plate having a plurality of slots and openings formedtherein; and a second impedance plate having a plurality of slots andopenings formed therein; the separator, first and second impedanceplates being stacked upon each other such that the second impedanceplate is disposed between the separator and first impedance plates, withthe slots and openings of the first and second impedance platescollectively defining certain ones of the fluid passageways.
 15. Theimpedance assembly of claim 13 wherein: at least some of the fluidpassageways are tortuous and define a series of turns which extend atgenerally right angles relative to each other; and the tortuous fluidpassageways of the impedance assembly define differing numbers of turns.16. The impedance assembly of claim 13 wherein the impedance assemblyfurther comprises: an upper cap; and a lower cap; the impedance plateassemblies being stacked between the upper and lower caps.
 17. Theimpedance assembly of claim 13 wherein the inflow end has a beveledconfiguration.
 18. The impedance assembly of claim 17 wherein theoutflow end has an arcuate configuration.
 19. The impedance assembly ofclaim 17 further comprising at least one layer of wire mesh attached tothe impedance assembly and covering the inflow end thereof.
 20. A methodof retrofitting a rotary valve including a rotary closure element whichdefines an outer surface, a bore and an axis of rotation, and isselectively movable between a fully open position and a fully closedposition with an impedance assembly, the method comprising the steps of:(a) securing a plurality of impedance plate assemblies to each other ina stacked arrangement along a plate assembly axis to form the impedanceassembly, each of the impedance plate assemblies including a pluralityof openings formed therein which collectively define a plurality offluid passageways extending from an inflow end to an outflow end of theimpedance assembly when the impedance plate assemblies are stacked uponeach other; and (b) mounting the impedance assembly within the bore ofthe closure element.
 21. The method of claim 20 wherein step (b)comprises mounting the impedance assembly within the bore such that thefluid passageways are each downstream of the axis of rotation.
 22. Themethod of claim 21 wherein step (b) comprises mounting the impedanceassembly within the bore such that portions of certain ones of the fluidpassageways are upstream of the axis of rotation.
 23. The method ofclaim 20 wherein step (b) comprises mounting the impedance assemblywithin the bore of the closure element such that the plate assembly axisextends in generally parallel relation to the axis of rotation.
 24. Avalve assembly, comprising: a rotary closure element defining an axis ofrotation and selectively movable between a fully open position and afully closed position; and an impedance assembly mounted to and movablewith the rotary closure element, the impedance assembly defining aninflow end and an outflow end, and comprising: a plurality of impedanceplate assemblies secured to each other in a stacked arrangement along anaxis which is generally parallel to the axis of rotation; each of theimpedance plate assemblies including a plurality of openings formedtherein which collectively define a plurality of fluid passagewaysextending from the inflow end to the outflow end when the impedanceplate assemblies are stacked upon each other.
 25. The valve assembly ofclaim 24 wherein the impedance assembly is configured and orientedrelative to the closure element such that the fluid passageways are eachdownstream of the axis of rotation when the closure element is in thefully open position.
 26. The valve assembly of claim 25 wherein theimpedance assembly is configured and oriented relative to the closureelement such that certain ones of the fluid passageways include portionswhich are upstream of the axis of rotation when the closure element isin the fully open position.
 27. The valve assembly of claim 24 wherein:at least some of the fluid passageways are tortuous and define a seriesof turns which extend at generally right angles relative to each other;and the tortuous fluid passageways of the impedance assembly definediffering numbers of turns.
 28. The valve assembly of claim 27 whereinthe impedance assembly is mounted to the closure element such that flowis applied initially to the tortuous passageways having a greater numberof turns when the closure element is moved from the fully closedposition toward the fully open position.